1. Field of the Invention
The present invention relates to an image blur suppression device for a camera or other optical devices, suppress to image blur caused, for example, by shaking the camera, and in particular to a vibration motor for use in driving an optical system of an image blur suppression device.
2. Description of the Related Art
Image blur suppression devices have as their object, suppression of, or reduction of, blurring in an image projected onto an image plane. A motion compensation device is a type of image blur suppression device which compensates for motion incident upon an optical system which projects the image onto the image plane. Motion is typically imparted to the optical system by way of vibrations in the optical system, or in the surrounding holding member. In general, known motion compensation devices cause a compensation lens to shift counter to the motion of the optical system so as to shift the image projected by the optical system relative to the optical system.
In recent years, progress has been made in the automation of cameras, for example, automatic exposure, automatic film winding, automatic speed lights, as well as automatic focus. As a result, photographs are easier to produce. However, the high magnification of zoom compact cameras, and in particular long focal point distance photography, increases the effect of image blur caused by camera shake.
Japanese Patent Publication Number Hei 3-110530, and Japanese Patent Publication Number Hei 5-95204, propose image blur suppression devices which attempt to prevent image blur by correcting camera shake during photography.
FIG. 33 is a perspective diagram of an example of a camera with a known blur image blur suppression device. An image blur suppression optical system 9 for a camera 1 generally comprises: angular velocity sensors 2 and 3 to detect motion in a horizontal direction (left and right movements of the camera in the yawing direction and X direction) and a vertical direction (up and down movements of the camera in the pitching direction and Y direction) in a plane orthogonal to an optical axis Z of the camera 1; two transmission gear arrays 5 and 6 which drive a lens frame 4, supporting a lens, in the X direction and Y direction respectively; and electro-magnetic motors 7 and 8 connected to transmission gear arrays 5 and 6, respectively. The lens frame 4 is shifted in the direction opposite to the direction of motion by activating electro-magnetic motors 7 and 8 based on the motion information obtained from the outputs of angular velocity sensors 2 and 3. In general, camera shake is compensated during photography and image blur is prevented by canceling the movement of the image by shifting the lens frame in a direction opposite to the direction of movement.
Because conventional image blur suppression devices use high speed rotation, low torque electro-magnetic motors 7 and 8 as the drive source, torque is increased by connecting the electro-magnetic motors 7 and 8 to gear arrays 5 and 6, which are speed reduction mechanisms. However, this increases the weight and size of the camera. Also, the gear arrays 5 and 6 are composed of multiple gears, increasing the number of parts, complicating the structure, and increasing the cost of manufacturing and assembling the parts. Further, backlash and inertia is imparted by the gears of transmission gear arrays 5 and 6. It is therefore fundamentally difficult to improve the extremely critical start-up responsiveness during activation creating unavoidable mechanical noise. In addition, to shift lens frame 4 independently in the X direction and Y direction respectively, it is necessary to provide transmission gear arrays as well as electro-magnetic motors for each direction. This leads to a large, heavy, complicated and noisy camera.